1. Field of the Invention
The present invention relates to a temperature compensating method and apparatus for an optical disc device, and more particularly to a method and apparatus in which a thermal sensor is used to detect the temperature of a laser diode to find out the proper power relative to the temperature and determine the power or clock for achieving the optimum record quality.
2. Description of the Prior Art
The adjusting operation of a light source in an optical disc device is to adjust the power of the light source to keep the power output constant. The light source of a conventional optical disc device is a laser diode. A front sensor is disposed near the laser diode to detect the power of the laser diode any time, and transmits the detected power to a controller controlling the emission of the laser diode to keep the power constant every time. However, the factor of deciding the record quality doesn't all depend on keeping the power constant, actually. Because the laser pick-up head has the temperature variation during recording, the temperature variation will change the wavelength of the light emitted from the laser pick-up head.
As shown in FIG. 1, the dye coated on a disc appears different sensitivities S for different wavelengths λ of light sources. Therefore, in order to achieve the optimum record quality, it is necessary for dicks of different materials to record with the wavelength relative to high sensitivity. However, with the increase of the recording time, the temperature of the laser pick-up head increases to cause the wavelength of the light emitted from the laser pick-up head to change. Consequently, the laser pick-up head loses the proper wavelength relative to high sensitivity to cause bad record quality. Therefore, it is desired to solve the problem of recording bad quality due to the temperature variation of the laser pick-up head.